The present invention relates to an electrically controlled lock for a door and is principally concerned with such locks that form part of a door closure installation which includes a latchbolt that is retractable under manual actuation of a lever or knob actuator disposed on at least one side of a door to which the lock is fitted to allow the door to be opened from a closed position.
Door closures that have the above kind of operation are well known in door installations and they can be locked to prevent door opening by a variety of different mechanisms. For example, some closures can be locked by arrangements which do not effect the operation of the levers or knobs, such as by a deadbolt which is operable independently of the levers or knobs. Alternatively, the lock may be arranged to act on the lever or knob such as to prevent its rotation so that the retracting mechanism for retracting the latchbolt cannot be actuated. Still alternatively, the lock can be arranged to act directly on the latchbolt retracting mechanism, or the latchbolt itself, to prevent latchbolt retraction. The present invention is concerned with arrangements of the latter kind, in which the door closure is locked when the latchbolt cannot be retracted.
It is an object of the present invention to provide an electrically controlled lock for a door closure which can assume either a locked or unlocked condition and in which movement between those conditions is controlled electronically. It is a further object of the invention to minimise the electric current drawn by the electronic control. It is still a further object to provide a mechanism to override the electronic control.
According to the present invention there is provided to an electrically controlled lock, including a retractable latchbolt and a clutch mechanism disposed between a latchbolt retracting mechanism for retracting said latchbolt and a drive member for driving said latchbolt retracting mechanism, said clutch mechanism including first and second engagable bodies which are connected to said drive member and said latchbolt retracting mechanism respectively, so that said drive member is operable to rotate said first engagable body and said latchbolt rectracting mechanism is operable upon rotation of said second engagable body, said engagable bodies being relatively movable between an engaged condition in which drive of said drive member is transmitted to said latchbolt retracting mechanism for retracting said latchbolt, and a disengaged condition in which transmission of drive between said drive member and said latchbolt retracting mechanism is interrupted so as to prevent retraction of said latchbolt, said relative movement of said engagable bodies occurring as a result of engagement of at least one of said bodies with an actuating member which is controlled by electrical actuating means to move between a non-actuated and an actuated position, in said non-actuated position said actuating member is disposed between said engagable bodies and is operable, upon drive by said drive member to rotate said first engagable body, to engage at least one of said first and second engagble bodies and to cause them to disengage, and in said actuated position, said actuating member is positioned to permit said engagable bodies to remain engaged upon rotation of said first engagable body by said drive member for transmission of drive through said second engagable body to said latchbolt retracting mechanism.
The actuating means can take any suitable form and can for example be an electrical motor that drives the actuating member. Alternatively the actuating means could be a solenoid and the actuating member is a plunger driven by the solenoid.
A lock according to the invention is advantageous for several reasons. In particular, electrically controlled locks are increasingly being used in commercial applications where access through a door is controlled by a signal recognition system, such as a validated magnetic or electric card or key system, which system reads a code and determines from that whether the door is to be unlocked. Such systems are useful not only to permit or prevent access through a door, but can also be used to electronically monitor and record movement past the door, such as the frequency and identity of personnel who gain door access.
An electrically controlled lock is further advantageous, as it can be programmed to react differently to the signals or codes of different personnel. Thus, personnel can be provided with different access availability by appropriate programming of the code reader. Reprogramming can also be relatively simple, so that the availability of access can be altered easily. Such reprogramming furthermore does not necessarily require the card or key to be programmed or changed. This differs from a traditional mechanical key system, in which access through a door is generally available as long as a person has in their possession, the relevant key. Thus, in that system access is difficult to control and if access is to be prevented, the key needs to be retrieved or the barrel of the lock changed. A further benefit of electrically controlled locks relates to the generally simplified unlocking of a door.
Electrically controlled locks have found widespread use in the hotel industry. In that industry, the locks can be programmed to permit a guest room door to be opened by a particular card given to a guest for the duration of his or her booking. At the end of that booking the lock can be reprogrammed so that further access to that guest by the card is not available. This renders the card ineffective to gain entry to the room until it is further reprogrammed. This is also a useful characteristic for other commercial and domestic buildings.
A lock according to the invention is applicable to installations in which a manually operable drive member is applied to only one side of the door, as well as to installations in which drive members are disposed on both sides of the door. The lock of the invention is particularly advantageous for installations of the latter kind in which a door is required to be opened from either side. In such installations, a drive member is disposed on either side of the door and a clutch mechanism may be applied to each drive member, or only one of those drive members. In an arrangement employing a clutch mechanism applied to only one of the drive members, the door can be locked from one side only and this arrangement is highly acceptable and preferred in many situations. In particular, that arrangement is preferred when the lock is applied to the door of a hotel guest room, because it facilitates easy egress from the room by operation of the drive member on the inside of the door which is permanently operable, but prevents entry through the door from the outside, unless the person attempting to gain entry has the correctly coded card, or other coded instrument. Accordingly, this system is also appropriate for areas to which restricted entry is gained past a door, but to which exit from that area need not be controlled.
A drive member which is suitable for the invention can be of a conventional form, such as a conventional drive lever or knob which can be rotated manually to operate the latchbolt retracting mechanism, with return rotation returning the latchbolt to its previous, normally extended position. Alternatively, the drive member may be of a different form and may itself may be electrically operated to activate the latchbolt retraction mechanism. The latchbolt retracting mechanism can also be of a conventional form, with modification as necessary to connect it to the clutch mechanism. Also, the electrical control that activates the actuating means can be of any suitable form which provides an electrical current in the desired manner.
In a preferred form, the engaging members of the clutch mechanism are cylindrical discs which in an engaged condition permit transmission of a drive load from the drive member to the latchbolt retracting mechanism by rotation of the engaging members. The engaging members can be engaged by any suitable means and in one arrangement, one of the engaging members includes at least one protruding portion that can be received within a recessed portion in the other of the engaging members and while the protruding portion remains received within the recessed portion, the drive load can be transmitted to the latchbolt retracting mechanism. The protruding and recessed portions are preferably disposed on facing engagable surfaces of the engaging members and separation of engaging members to remove the protruding portion(s) from the recess(es) serves to disengage the clutch mechanism.
The surface which is engaged by the actuating member may be provided in a recess and that recess may be formed on one of the engaging members, or be partially formed in both of the engaging members. The recess is preferably formed at the perimeter of the or each engaging member, particularly if these are formed as discs. Preferably the recess arrangement is such that the end of the actuating member can be accommodated in the recess without disengaging the engaging members until such time as the drive member is rotated. In that arrangement, the recess can be arranged, so that movement of the engaging member connected to the drive member is influenced by its engagement with the actuating member to move in a direction that disengages it from the other of the engaging members. Thus, in this arrangement, disengagement of the clutch mechanism only takes place when the drive member is operated. This arrangement is advantageous, in that the end of the actuating member can be disposed within the recess at all times and when the drive member is operated, the engaging bodies will be separated so that access through the door cannot be obtained. Advantageously, the actuating member can be removed from the recess by actuation of the solenoid actuator and in that removed condition, a rotational force applied to the drive member will be transmitted to the latchbolt retracting mechanism through the engaged clutch mechanism.
Where the recess is formed partially on both engaging members, the separate recess surfaces may be formed differently for engagement with the actuating member. In particular, one of the surfaces may include a profile that causes displacement of one engaging body relative to the other, such as by a ramped surface. Alternatively, all surfaces that come into contact with the actuating member may be contoured to promote the desired separation and these may also include appropriate abutment services to prevent rotation of the engaging members beyond a certain degree.
The present invention further provides an override mechanism which prevents disengagement of the clutch mechanism by the actuating means. The override mechanism is provided as a means to unlock a door when the means normally provided for that purpose has failed. That failure may be due to a lack of electrical energy, or to a mechanical breakdown in the actuating means, or to misplacement or loss of the card that actuates the actuating means.
It is a principle function of the override mechanism that the actuating member is removed from the position at which it disengages the clutch mechanism so that the latchbolt can be retracted by rotation of the drive member. This can be achieved in any suitable manner, but in a preferred form, the override mechanism causes movement of the actuating member to a position in which the plunger end cannot adopt the disengagement position relative to the clutch mechanism. That movement can be in any suitable direction and in a preferred form the movement is rotary. Alternatively the movement can be linear. The override mechanism can be operated by mechanical or electrical means and in a preferred form includes a cylinder assembly that is key operated and the barrel of which rotates in engagement with the actuating member, to displace the actuator or which causes the actuating member to be displaced from the disengaging position.